No, this is the backlash from the Church's mismanagement.
No, that's just an excuse. Certain people are bored, or need to distract their nobility with an external focus. So, classic maneuver: start a war. Most of the realm nobility follow along.
Certain other people are angry that their individual agenda was not adopted. Or that they didn't get the power/position they feel they deserved.
And some people just have a persecution complex, and lash out mindlessly.